Proteins - NATS1560 Understanding Food PDF

PROTEINS Matthew Kinsey, Still Life with Eggs Walnuts and Copper Vessel, 2010 NATS1560 UNDERSTANDING FOOD For class use only. Do not circulate.  LEARNING OBJECTIVES To explain the molecular composition of proteins and their “building blocks”, the amino acids To explain the diff...

PROTEINS Matthew Kinsey, Still Life with Eggs Walnuts and Copper Vessel, 2010 NATS1560 UNDERSTANDING FOOD For class use only. Do not circulate.  LEARNING OBJECTIVES To explain the molecular composition of proteins and their “building blocks”, the amino acids To explain the difference between essential, non-essential, and conditionally essential amino acids To list the diverse functions of proteins in the body 2  PROTEINS Proteins are polymers composed of amino acids Amino acid = molecule composed of an amine (- NH2), a carboxylic acid (- COOH), and a “side chain” - the side chain is different in each amino acid Polypeptide: sequence of amino acids Protein: polypeptide folded into a specific complex tridimensional shape Every protein is characterized by its specific sequence of amino acids and its specific shape 3  AMINO ACIDS Twenty amino acids are coded by DNA and used by living organisms essential: the human body needs to obtain them from food conditionally essential amino acids: the human body may need to obtain them from food under certain conditions Amino acids Essential Conditionally essential Non essential histidine arginine alanine isoleucine cysteine asparagine leucine glutamine aspartic acid lysine glycine glutamic acid methionine proline phenylalanine serine threonine tyrosine tryptophan valine 4  THE FUNCTIONS OF PROTEINS structure (e.g., keratin and collagen) enzymes (e.g., lactase) some hormones (e.g., somatotropin, insulin) muscle contraction (actin and myosin) immune system (antibodies) transport and cellular communication (e.g., hemoglobin) energy 5  FOOD SOURCES OF PROTEINS Complete sources of essential amino acids: eggs, meat, fish, milk and milk products, soybeans, quinoa, amaranth Combinations of Incomplete sources of ingredients in dishes amino acids: legumes and diets can provide the full assortment of or pulses, grains, nuts, essential amino acids. seeds, some vegetables, and some fruits 6  REVIEW What are the “building blocks” of proteins? What is the difference between essential, non essential, and conditionally essential amino acids? What are functions of proteins in the body? Give a few specific examples What are the main food sources of proteins? 7